Coughing up phlegm is caused by respiratory tract infections, bronchitis, and increased inflammatory secretions. One year old babies are too young to cough up phlegm on their own and are unable to expel the phlegm when coughing, so the phlegm tends to accumulate in the trachea, resulting in a thick and sticky phlegm that can’t be discharged. In this case, the first thing you need to do is to give your child plenty of warm water to dilute the phlegm. Take anti-inflammatory and phlegm dissolving medicines, such as Amoxicillin Clavulanate Potassium Granules, Bromhexine Hydrochloride Combination, Ambroxol Hydrochloride Oral Solution and other medicines for treatment. Normally, you can gently pat the front, side and back of the chest to loosen the phlegm and promote the discharge of phlegm. Help your child to clean the secretions in the mouth in a timely manner. The child should not eat too fast when eating, so as to avoid choking and coughing, but also need to keep the indoor air humidity is appropriate, avoid excessive dryness and cold air stimulation, so as not to exacerbate the symptoms of coughing.